U.S. patent application number 11/941570 was filed with the patent office on 2009-05-21 for individually unique hybrid printed antennae for chipless rfid applications.
This patent application is currently assigned to XEROX CORPORATION. Invention is credited to Naveen CHOPRA, Peter M. KAZMAIER, Paul F. SMITH.
Application Number | 20090128290 11/941570 |
Document ID | / |
Family ID | 40394301 |
Filed Date | 2009-05-21 |
United States Patent
Application |
20090128290 |
Kind Code |
A1 |
CHOPRA; Naveen ; et
al. |
May 21, 2009 |
INDIVIDUALLY UNIQUE HYBRID PRINTED ANTENNAE FOR CHIPLESS RFID
APPLICATIONS
Abstract
A method of printing chipless RFID tags with unique features,
includes printing a RFID antenna pattern precursor using a first
printing process, wherein the RFID antenna pattern precursor
includes a plurality of disconnected wire segments; and printing a
conductive ink using a second print process to interconnect at
least two of the plurality of disconnected wire segments, to
produce a final RFID antenna with a unique antenna geometry.
Inventors: |
CHOPRA; Naveen; (Oakville,
CA) ; KAZMAIER; Peter M.; (Mississauga, CA) ;
SMITH; Paul F.; (Oakville, CA) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC.
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
XEROX CORPORATION
Norwalk
CT
|
Family ID: |
40394301 |
Appl. No.: |
11/941570 |
Filed: |
November 16, 2007 |
Current U.S.
Class: |
340/10.1 ;
427/98.4 |
Current CPC
Class: |
G06K 19/0672 20130101;
H05K 3/1241 20130101; H05K 1/165 20130101; Y10T 29/49018 20150115;
H05K 3/12 20130101; Y10T 29/49128 20150115; G06K 19/07779 20130101;
G06K 19/07784 20130101; G06K 19/07783 20130101; H05K 2203/1476
20130101; Y10T 29/49016 20150115; Y10T 29/49155 20150115 |
Class at
Publication: |
340/10.1 ;
427/98.4 |
International
Class: |
H04B 7/00 20060101
H04B007/00; B05D 5/12 20060101 B05D005/12 |
Claims
1. A method of printing chipless RFID tags with unique features,
comprising: printing a RFID antenna pattern precursor using a first
printing process, wherein the RFID antenna pattern precursor
comprises a plurality of disconnected wire segments; and printing a
conductive ink using a second printing process to interconnect at
least two of said plurality of disconnected wire segments, to
produce a final RFID antenna with a unique antenna geometry;
wherein the second printing process is a digital printing process,
and the number of disconnected wire segments that are
interconnected, and/or the pattern in which they are connected,
during the second printing process is customized based on
information inputted into the digital printing process.
2. The method according to claim 1, wherein the first printing
process is an analog printing process.
3. The method according to claim 1, wherein the first printing
process is selected from the group consisting of gravure,
rotogravure, flexography, and screenprinting.
4. (canceled)
5. The method according to claim 1, wherein the second printing
process is inkjet printing.
6. The method according to claim 1, wherein the conductive ink
comprises a material selected from the group consisting of
graphite, copper, gold, nickel, silver, aluminum, platinum, and
mixtures thereof.
7. The method according to claim 1, wherein different ones of the
plurality of disconnected wire segments can be interconnected to
provide different unique antenna geometries.
8. The method according to claim 1, wherein the different unique
antenna geometries are different antenna shapes or different
antenna lengths.
9. The method according to claim 8, wherein the different unique
antenna geometries correspond to unique resonance frequencies.
10. The method according to claim 1, wherein all of the plurality
of disconnected wire segments are interconnected.
11. The method according to claim 1, wherein at the conclusion of
the second printing process, less than all of the plurality of
disconnected wire segments are interconnected.
12. The method according to claim 1, wherein at least 50% of a
final antenna length of the RFID antenna is derived from the
disconnected wire segments of the antenna master.
13. The method according to claim 1, wherein the number of
disconnected wire segments connected by a single interconnect is
two or more.
14. The method according to claim 1, further comprising one or more
steps selected from the group consisting of an overcoating step and
a drying step.
15-20. (canceled)
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates to printing unique printed antennae
using a hybrid analog/digital printing system.
BACKGROUND
[0002] Recently, radio frequency identification (RFID) technology
has gained tremendous popularity as a device for storing and
transmitting information. RFID technology utilizes a tag
transponder, which is placed on an object, and a reader, also
referred to herein as an interrogator, to read and identify the
tag. RFID technologies are broadly categorized as using either
"active" tags or "passive" tags. Active tags have a local power
source (such as a battery) so that the active tag sends a signal to
be read by the interrogator. Active tags have a longer signal
range. "Passive" tags, in contrast, have no internal power source.
Instead, passive tags derive power from the reader, and the passive
tag re-transmits or transponds information upon receiving the
signal from the reader. Passive tags have a much shorter signal
range (typically less than 20 feet).
[0003] Both categories of tags have an electronic circuit that is
typically in the form of an integrated circuit or silicon chip. The
circuit stores and communicates identification data to the reader.
In addition to the chip, the tag includes some form of antenna that
is electrically connected to the chip. Active tags incorporate an
antenna that communicates with the reader from the tag's own power
source. For passive tags, the antenna acts as a transducer to
convert radio frequency (RF) energy originating from the reader to
electrical power. The chip then becomes energized and performs the
communication function with the reader.
[0004] On the other hand, a chipless RFID tag has neither an
integrated circuit nor discrete electronic components, such as the
transistor or coil. This feature allows chipless RFID tags to be
printed directly onto a substrate at lower costs than traditional
RFID tags.
[0005] As a practical matter, RFID technology uses radio
frequencies that have much better penetration characteristics to
material than do optical signals, and will work under more hostile
environmental conditions than bar code labels. Therefore, the RFID
tags may be read through paint, water, dirt, dust, human bodies,
concrete, or through the tagged item itself. RFID tags may be used
in managing inventory, automatic identification of cars on toil
roads, security systems, electronic access cards, keyless entry and
the like.
[0006] Antennae are an element of RFID tags that are typically
prepared via stamping/etching techniques, wherein a foil master is
carved away to create the final structure. The RFID antenna may
also be printed directly on the substrate using a conductive metal
ink. The ink is printed on a substrate, followed by high
temperature sintering in order to anneal the particles and to
create a conductive line on the substrate. Alternatively, metal
fibers may be incorporated directly into the substrate. For
example, one chipless RFID technology from Inkode.RTM. Corp. uses
embedded aluminum fibers that are embedded into paper. The aluminum
fibers must be cut to the appropriate wavelength (1/4 wavelength)
and be incorporated into the paper fibers as a furnish additive
during the papermaking process. Therefore, the Inkode.RTM. method
is costly and tedious.
[0007] Although particulate metal materials may be used, the
superior characteristics of nanoparticle metal materials in ink
applications yields a better product. Metallic nanoparticles are
particles having a diameter in the submicron size range.
Nanoparticle metals have unique properties, which differ from those
of bulk and atomic species. Metallic nanoparticles are
characterized by enhanced reactivity of the surface atoms, high
electric conductivity, and unique optical properties. For example,
nanoparticles have a lower melting point than bulk metal, and a
lower sintering temperature than that of bulk metal. The unique
properties of metal nanoparticles result from their distinct
electronic structure and from their extremely large surface area
and high percentage of surface atoms.
[0008] Metallic nanoparticles are either crystalline or amorphous
materials. They can be composed of pure metal, such as silver,
gold, copper, etc., or a mixture of metals, such as alloys, or core
of one or more metals such as copper covered by a shell of one or
more other metals such as gold or silver. The nozzles in an inkjet
printing head are approximately 1 .mu.m in diameter. In order to
jet a stream of particles through a nozzle, the particles' size
should be less than approximately one-tenth of the nozzle diameter.
This means that in order to inkjet a particle, its diameter must be
less than about 100 nm.
[0009] Nickel has been used for conductive inks for a very limited
extent because of its relatively low conductivity (approximately
four times less than that of copper). Gold and silver can provide
good conductivity, but are relatively expensive. Moreover, gold and
silver require high temperatures for annealing, which can pose a
challenge for printing on paper and plastic substrates. Copper
provides good conductivity at a low price (about one percent of
that of silver). Unfortunately, copper is easily oxidized and the
oxide is non-conductive.
[0010] Copper-based nanoparticle inks are unstable and require an
inert/reducing atmosphere during preparation and annealing in order
to prevent spontaneous oxidation to non-conductive CuO or
Cu.sub.2O. Copper polymer thick film (PFT) inks have been available
for many years and can be used for special purposes, for example,
where solderability is required. Another interesting strategy is to
combine the advantages of both silver and copper. Silver plated
copper particles are commercially available, and are used in some
commercially available inks. Silver plating provides the advantages
of silver for inter-particle contacts, while using the cheaper
conductive metal (copper) for the bulk of the particle material.
Thus, the only reliable means of preparing copper antennae is via
electroplating on an existing metal surface.
[0011] Hybrid printing technology combines analog printing
processes (such as offset lithography, flexography, etching, and
letterpress printing) with digital printing processes (such as
inkjet printing). In hybrid printing processes, inkjet printing is
one particularly suitable digital printing method, because it can
easily be integrated with other processes and machines. Hybrid
printing technology has been used, for instance, to customize
marketing material. An analog process is used to print the
marketing material itself, while a digital process is used to add
information only relevant to individual consumers.
[0012] Hybrid printing systems offer numerous advantages, for
example, the high quality color production of analog methods and
the filly variable printing capability of digital technology.
Additionally, the workflow and job processing improvements that
hybrid printing enables can have a significant economic impact on a
plant's operations. Because hybrid systems enables a job to be
completed, from a blank substrate to a finished product, in a
single operation, hybrid systems minimizes material handling steps,
work-in-process inventories, and a lot of labor that typically goes
into such jobs when run in multiple steps. This, in turn, saves
time and money, while reducing waste and drastically reducing the
need for inventories.
[0013] U.S. Pat. No. 6,737,204 B2 to Swihart describes creating a
hybrid digital/analog image, wherein an analog image is formed
directly on a digitally generated image.
[0014] A printed antenna is one path towards chipless RFID tags,
but the challenge lies in printing many RFID with unique features
for item-level tagging. One method of creating RFID tags with
unique features is to print each RFID tag individually via inkjet
printing. However, this method is costly and highly time-consuming.
Thus, there exists a need for a cheaper method of making RFID tags
with unique features.
SUMMARY
[0015] The present disclosure provides for a method of printing
chipless RFID tags with unique features, comprising: printing a
RFID antenna pattern precursor using a first printing process,
wherein the RFID antenna pattern precursor comprises a plurality of
preprinted wire segments that constitute a majority of the RFID
antenna pattern; and printing a conductive ink using a second
printing process to interconnect at least two of said plurality of
preprinted wire segments, to produce a final RFID chip with a
unique antenna geometry.
[0016] The present disclosure also provides for a chipless RFID tag
with unique features, comprised of: an RFID antenna precursor
printed by a first printing process, wherein the RFID antenna
pattern precursor comprises a plurality of preprinted wire segments
that constitute a majority of the RFID antenna pattern; and a
conductive ink printing printed by a second printing process,
wherein the conductive ink interconnect at least two of the
plurality of preprinted wire segments, to produce a final RFID chip
with a unique antenna geometry.
[0017] There are numerous advantages to the present disclosure.
Speedy and efficient mass production of RFID antenna masters is
achieved via analog printing, as large numbers of identical master
patterns can be created by using a fast printing process.
Additionally, customization of each individual mass-produced RFID
tag is achieved by digital printing. Furthermore, using the
relatively slower digital process (for example, inkjet printing) to
add just a few unique features will minimize the time lag for
printing. Also, the use of inkjet printing allows for very fine
variable features to be printed, thus widening the scope of unique
features and materials that may be printed. For example, graphite
inks and copper may be used. Conversely, printing of only small
areas of the antenna with conductive ink (such as gold, for
enhanced conductivity at the interconnections) saves considerable
amount of money as when compared against printing an entire
antenna. Thus, the ability to print a variable data RFID tag in
large volumes at low cost is now possible for the first time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a depiction of an RFID master according to an
embodiment of this disclosure.
[0019] FIG. 2 is a depiction of the preprinted wires of the RFID
master interconnected by printed interconnects to produce a small
antenna.
[0020] FIG. 3 is a depiction of the preprinted wires of the RFID
master interconnected by printed interconnects to produce a medium
antenna.
[0021] FIG. 4 is a depiction of the preprinted wires of the RFID
master interconnected by printed interconnects to produce a large
antenna.
[0022] FIG. 5 is a depiction of a finished RFID tag with a large
antenna.
DETAILED DESCRIPTION OF EMBODIMENTS
[0023] This disclosure is not limited to particular embodiments
described herein, and some components and processes may be varied
by one of ordinary skill in the art, based on this disclosure. The
terminology used herein is for the purpose of describing particular
embodiments only, and is not intended to be limiting.
[0024] In this specification and the claims that follow, singular
forms such as "a," "an," and "the" include plural forms unless the
content clearly dictates otherwise. In addition, reference may be
made to a number of terms that shall be defined as follows:
[0025] The phrase "antenna geometry" refers to the overall design,
including length, surface area, and geometric shape, of the antenna
structure. The phrase "antenna geometry" thus generally only refers
to the interconnected wiring segments, and excludes any
non-connected wiring segments that may still be repent from the
antenna master. However, in some embodiments where the
non-connected wiring segments may affect the performance, such as
frequency or response of the antenna, such non-connected wiring
segments may still be considered part of the antenna geometry.
[0026] "RFID antenna pattern precursor" and "antenna master" refer
to a plurality of disconnected segments, some or all of which
segments may be subsequently connected to form a desired final
antenna structure.
[0027] In general, the present disclosure provides a method of
printing unique chipless RFID tags by inexpensively mass-producing
non-unique RFID antenna pattern precursors (antenna masters) with
preprinted wire segments, followed by turning the non-unique RFID
antenna pattern precursors into desired unique RFID antenna
patterns by interconnecting two or more of the preprinted wire
segments. For example, in one embodiment, the present disclosure
provides a method of printing unique chipless RFID tags by
inexpensively mass-producing non-unique RFID antenna pattern
precursors (antenna masters) with preprinted wire segments by an
analog printing method. The non-unique RFID antenna pattern
precursors are then generally turned into desired unique RFID
antenna patterns, such as finished chipless RFID tags, by a digital
printing method, such as inkjet printing. In the inkjet printing
step, conductive ink is used to print unique marking onto the RFID
antenna precursors to connect two or more of the preprinted wire
segments. The antenna lengths (that is, the length of the antenna
corresponding to interconnected wire segments) on the RFID tags
vary, and the various antenna lengths correspond to unique
resonance frequencies. After the wire segments are connected by the
interconnects, the antenna loop is completed by printing a
dielectric barrier over the wires, followed by a bridge wire
joining the center terminus and the outside terminus. Therefore,
the finished RFID tags will each have unique response determined by
the antenna geometry formed by interconnection of specific wire
segments of the antenna master.
[0028] For purposes of description only, FIGS. 1-5 depict the
creation of a unique chipless RFID tag antenna according to one
embodiment of the disclosure. FIG. 1 depicts a sample mass-produced
antenna master produced, for example, via an analog printing
method. The antenna master 1 is generally made up of a plurality of
separate wire segments 2. Although FIG. 1 shows only ten separate
wire segments 2, it is understood that the antenna master can have
any number of separate wire segments, and those separate wire
segments can be located in any spatial orientation. The separate
wire segments 2 are separated by respective gaps 3 that, if two or
more are interconnected, would extend the antenna length. In this
manner, the bulk or majority of the antenna master pattern can be
printed via an analog printing method. Unique features can then be
added to the antenna master via, for example, digital printing in
order to eventually create a finished chipless RFID tag with unique
resonance frequency.
[0029] FIG. 2 depicts one exemplary unfinished chipless RFID tag in
its intermediate form, with a relatively small antenna geometry or
antenna length. In FIG. 2, the antenna master 1 of FIG. 1 is
digitally printed to connect wire segments 2 of the preprinted
antenna master 1 by adding connecting segments 4 in desired antenna
segment gaps 3. In this embodiment, three antenna segment gaps 3
are filled with connecting segments 4 to interconnect four of the
ten wire segments 2 to thereby provide a relatively short antenna
length. This accordingly provides to the antenna master a unique
antenna geometry on the RFID tag precursor. The antennae length is
inversely proportional to resonance frequency. Thus, the small
antenna length corresponds to high resonance frequency. The antenna
loop will be completed to produce a finished RFID tag (shown in
FIG. 5). Therefore, the finished RFID tags will each have unique
response determined by the antenna geometry formed by
interconnection of specific wire segments of the antenna
master.
[0030] FIG. 3 depicts another exemplary unfinished chipless RFID
tag in its intermediate form with a relatively medium antenna
geometry or antenna length. In FIG. 3, the antenna master 1 of FIG.
1 is digitally printed to connect wire segments 2 of the preprinted
antenna master 1 by adding connecting segments 4 in desired antenna
segment gaps 3. In this embodiment, six antenna segment gaps 3 are
filled with connecting segments 4 to interconnect seven of the ten
wire segments 2 to thereby provide a relatively medium antenna
length. This accordingly provides to the antenna master a unique
antenna geometry on the RFID tag precursor. The medium antennae
length corresponds to medium resonance frequency. The antenna loop
will be completed to produce a finished RFID tag (shown in FIG. 5).
Therefore, the finished RFID tags will each have unique response
determined by the antenna geometry formed by interconnection of
specific wire segments of the antenna master.
[0031] FIG. 4 depicts one exemplary unfinished chipless RFID tag in
its intermediate form with a relatively long antenna geometry or
antenna length. In FIG. 4, the antenna master 1 of FIG. 1 is
digitally printed to connect wire segments 2 of the preprinted
antenna master 1 by adding connecting segments 4 in desired antenna
segment gaps 3. In this embodiment, one antenna segment gaps 3 are
filled with connecting segments 4 to interconnect all ten of the
wire segments 2 to thereby provide a relatively long antenna
length. This accordingly provides to the antenna master a unique
antenna geometry on the finished RFID tag. The large antennae
length corresponds to low resonance frequency. The antenna loop
will be completed to produce a finished RFID tag (shown in FIG. 5).
Therefore, the finished RFID tags will each have unique response
determined by the antenna geometry formed by interconnection of
specific wire segments of the antenna master.
[0032] FIG. 5 depicts one exemplary finished chipless RFID tag with
a relatively long antenna geometry or antenna length. In FIG. 5,
the wire segments 2 are connected by the connecting segments 4. The
antenna loop is completed by printing a dielectric barrier 7 over
the wires, followed by a bridge wire 6 joining the center terminus
5b and the outside terminus 5a.
[0033] The Antenna Master
[0034] The antenna master is a mass-produced precursor to a
finished antenna product. Thus, the antenna master is a printed set
of wire segments, which can be subsequently processed to provide a
plurality of unique final antenna geometries.
[0035] In embodiments, the antenna master features the bulk of the
antenna pattern. That is, in the interest of providing an economic
antenna master that can be mass-produced and then specifically
tailored to a number of different final antenna geometries, it is
desired that the antenna master provides at least a majority of the
final antenna geometry. For example, the antenna master can provide
a plurality of wire segments, such that more than 50% of the final
antenna length, being some or all of the wire segments of the
antenna master having been interconnected, is derived from the
antenna master. In other embodiments, the final antenna length
derived from the antenna master can be about 60% or more, about 70%
or more, about 80% or more, or about 90% or more. Likewise, to
provide specific unique tailoring of the antenna geometry from the
antenna master, in embodiments, no more than about 99% of the final
antenna length is derived from the antenna master. For example, the
final antenna length derived fiom the antenna master can be no more
than about 98%, no more than about 97%, no more than about 95%, or
no more than about 90%. Of course, in other embodiments, the
antenna master can provide less than 50% of the final antenna
length. While such embodiments may increase the production cost by
decreasing the mass-produced portion, they may allow for an
increased number of possible unique antenna geometries.
[0036] The antenna master can be created as a plurality of
disconnected wire segments that have been printed via an analog
printing process. Thus, the antenna master provides wire segments
that can be connected during a subsequent step, such as a digital
printing step, in order to produce the finished antenna. Generally,
the number of disconnected wire segments that can be provided in
the antenna master can range from two or greater to about 100. In
an exemplary embodiment, the number of disconnected wire segments
is from about 2 to about 20.
[0037] The antenna master may have a geometry of any shape and/or
pattern, and is not limited to the rectangular configurations as
shown in FIG. 1. For example, the overall shape of the antenna
master may be polygonal or non-polygonal, symmetrical or
non-symmetrical, and angular and/or round. Likewise, the
disconnected segments may be printed in random configurations that
can be specifically connected in different patterns in the
subsequent digital printing step. Moreover, the gaps created by the
disconnected segments are not limited to those as shown in FIG. 1.
Instead, the number, spacing, and size of gaps created on a single
antenna master can vary, and can be regular or not, as desired. For
example, the gaps can be located anywhere on the antenna master,
and may be located at random or at regularly spaced intervals. The
gaps can be of any length or width, and the size of the gaps
created by the disconnected segments on the antenna master may or
may not be uniform.
[0038] The Printing Process
[0039] For printing the antenna master, any suitable printing
methods may be used. For example, suitable methods include, without
limitation, roll-to-roll high volume printing method, such as
gravure, rotogravure, flexography, lithography, etching,
screenprinting, and the like. In embodiments, the process for
printing the antenna master is an analog process, as such processes
are typically better suited for high-volume, mass production
printing. Such processes thus economically allow the antenna master
to be printed, and then a subsequent process can be used to form
the final antenna geometries. Of course, digital or slower printing
processes can also be used to print the antenna master, although
such processes may slow the overall production process.
[0040] As desired, the antenna masters may be printed on any
suitable substrate. For example, the substrate can be paper, glass
art paper, bond paper, paperboard, Kraft paper, cardboard,
semi-synthetic paper or plastic sheets, such as polyester or
polyethylene sheets, and the like. These various substrates can be
provided in their natural state, such as uncoated paper, or they
can be provided in modified forms, such as coated or treated papers
or cardboard, printed papers or cardboard, and the like. Further,
the antenna masters can be printed one to a sheet, such as where
the antenna master is being printed onto a packaging material, or
they can be printed as a plurality of antenna masters on a single
sheet, such as where the antenna masters are printed onto a roll of
paper, onto labels, or onto a sheet that will sub subsequently
separated into multiple pieces.
[0041] Likewise, for printing the interconnections with conductive
ink, any suitable printing methods may be used. For example,
suitable printing methods include, without limitation, inkjet,
thermography, electrophotography, electrography, laser induced
transfer, inkjet printing, or a combination thereof. If a laser
induced transfer digital printing method is used, exemplary methods
of such method are dye sublimination, ablation, melt transfer, or
film transfer. In embodiments, the process for interconnecting the
wire segments of the antenna master is a digital process, as such
processes are typically better suited for printing unique patterns
that may be required for interconnecting the wire segments in
unique patterns. Such processes thus economically allow the unique
antenna geometry to be formed. Because digital printing processes
are generally slower and less economical than analog methods such
as those used to print the antenna master, it is desired in
embodiments to minimize the printing that is done by the digital
process. Thus, for example, the digital printing is used only to
print the small interconnects rather than the entire antenna
geometry. Of course, analog or faster printing processes can also
be used to print the antenna interconnects, particularly where a
large number of less unique structures may be desired.
[0042] Depending on the type of RFID tag being printed, the final
step involves digitally printing the dielectric bridge and joining
segment to connect the center terminus end and the outer terminus
end of the antenna in order to form a loop. Thus, the overall
printing process can generally be characterized as a analog-digital
printing process. However, if desired, the order of the digital and
analog printing steps may be inversed, so that the digital printing
step prints the interconnects first, then followed by the analog
printing of the antenna master, and finally finished with the
digital printing of the bridge area (dielectric and conductive
connection).
[0043] For printing the antenna master in the analog printing step,
any suitable conductive ink nay be used. Examples of such suitable
conductive inks include, without limitation, Parmod.RTM. inks
available from Parelec, Inc. These are generally high-viscosity
inks or pastes containing conductive metal flakes that are too
thick to be ink jet printed, and are well-suited for analog
printing (i.e. gravure, roll-to-roll, etc.). For printing the
interconnects in the digital printing step, any suitable conductive
ink may be used. Generally, suitable inks can be inks containing
graphite, platinum, gold, silver, aluminum, nickel, copper, or a
mixture thereof. In an exemplary embodiment, the conductive ink
containing copper is used.
[0044] In the digital printing step, the number of preprinted
disconnected segments connected by a single interconnect can be two
or more. Thus, one interconnect may connect multiple wire segments.
Moreover, an interconnect need not be placed at the shortest path
between two wire segments.
[0045] The widths and lengths of the preprinted disconnected
segments and interconnects may range from about 0.1 mm to about 10
mm for width, and from about 0.1 mm to about 35 m for length.
Moreover, the widths of the preprinted disconnected segments and
interconnects may differ, so that the width of the preprinted
disconnected segments are thicker than that of the interconnects,
or vice versa. Naturally, the lengths of preprinted disconnected
segments and interconnects may also differ.
[0046] Additionally, the widths and/or lengths of the preprinted
disconnected segments and/or the interconnects of a single finished
antenna may vary. Therefore, an exemplary antenna may consist of
preprinted disconnected segments and/or interconnects of various
widths and/or lengths.
[0047] Additional Processing Steps
[0048] Optionally, additional processing steps, such as any of
overcoating, drying and rinsing, alone or in combination, may
follow the printing steps.
[0049] For the optional overcoating step, any suitable overcoating
may be applied after the printing process is completed. For
example, a suitable overcoating can be applied to cover and protect
the printed metal wires, such as to protect them from abrasion.
When so applied, the overcoating can be of any desired thickness,
opacity, transparency, or the like.
[0050] Additionally, an optional drying step may follow the first
and/or the second printing steps. During the drying step, the ink
is allowed to dry for about 5 minutes at about 80.degree. C.
[0051] Finally, an optional sintering step follows the printing
step. This step may be performed at about 130.degree. C. for about
30 minutes.
[0052] It will be appreciated that various of the above-disclosed
and other features and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Also, various presently unforeseen or unanticipated
alternatives, modifications, variations or improvements therein may
be subsequently made by those skilled in the art, and are also
intended to be encompassed by the following claims.
EXAMPLES
[0053] Printing the Antenna Master
[0054] An antenna master (with 1 mm gaps) with a footprint of
approximately 4 cm.times.4 cm square, consisting of 8 turns, with a
width of 1 mm lines, and 0.5 mm space between adjacent lines and a
total virtual length of 33 m (and virtual resonant frequency of 9
MHz) was printed using a gravure process using a commercially
available silver ink on coated photographic paper. The print was
allowed to dry for 5 minutes at 80.degree. C. to allow volatile
carriers to evaporate off, leaving a paste residue.
Example 1
Printing a 6-Turn Antenna from Antenna Master
[0055] The first 6 turns (from the center) were completed on the
above-prepared antenna master by printing interconnects in the
first 12 gaps, using a Dimatix ink jet printer containing a
conductive copper or silver ink. Next, a dielectric bridge was
printed over the 6 completed loops, followed by an overlaying
bridge wire between the center of the antenna and the terminus of
the sixth loop. The length of the 6-turn antenna was 32.698 m,
which corresponds to a resonance frequency of 9.17 MHz.
Example 2
Printing a 3-Turn Antenna from Antenna Master
[0056] The first 3 turns (from the center) were completed on the
above-prepared antenna master by printing over the first 6 gaps,
using a Dimatix ink jet printer containing a copper or silver ink.
Next, a dielectric bridge was printed over the 3 completed loops,
followed by an overlaying bridge wire between the centre of the
antenna and the terminus of the third loop. The 3-turn antenna
length was 32.564 m, which corresponds to a resonance frequency of
21 MHz.
* * * * *